Note 13 - Fair Value Measurements - Fair Value Adjustments for Assets Measured On a Nonrecurring Basis (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Net decrease in fair value:
Fair value adjustments	$ 484	$ 163	$ 526	$ 229
Impaired Loans [Member]
Net decrease in fair value:
Fair value adjustments	22	25	47	27
OREO [Member]
Net decrease in fair value:
Fair value adjustments	$ 462	$ 138	$ 479	$ 202